Flange type duct joint assembly and seal arrangement therefor

ABSTRACT

A joint assembly for connecting the ends of a pair of generally rectangular sheet metal duct sections includes a pair of frame members secured to each other and connected to the respective duct end sections. The frame members each include four flange portions. Each flange portion has an upstanding channel shaped leg portion and an angularly extending duct receiving leg portion. A corner piece connects adjacent flange portions and extends into the channel portions of the upstanding leg portions to form the generally rectangular frame. The end portions of the ducts are inserted into longitudinal openings of the duct receiving leg portions. A flowing type gasket material is positioned longitudinally in the flanges in a longitudinal pocket formed between an inturned rebent portion and the upper horizontal surface of the bottom wall of the duct receiving leg portion. The end of each duct wall partially displaces the gasket material so that the gasket material extrudes outwardly around the upper and lower surfaces of the duct wall and between the ends of the flange portion and the corner piece. The surface of the corner piece flange portion is displaced from the front vertical wall of the upstanding channel shaped leg portion so that the edge of the duct extends beyond the flange portion and penetrates an outside gasket member positioned on the upstanding channel shaped leg portion and the corner piece. This provides an effective seal to prevent air within the duct from flowing around the end of the duct and between the outer surface of the duct and the surface of the flange portion of the corner piece.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of application Ser. No. 933,179 filedAug. 14, 1978, entitled "A Flange Type Duct Joint Assembly And SealArrangement Therefor" which is a continuation-in-part of U.S.application Ser. No. 872,644 filed Jan. 26, 1978 in the U.S. PatentOffice and now U.S. Pat. No. 4,218,079 issued Aug. 19, 1980, nowentitled "Flange Type Duct Joint Assembly".

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a joint assembly for sealingly connecting theends of a pair of sheet metal duct sections and more particularly to ajoint assembly that includes a pair of frame members having flangeportions secured to each other by angular corner pieces havingrearwardly curved or displaced flange portions operable to facilitate anair-tight seal between the ends of the duct sections and the framemembers.

2. Description of the Prior Art

U.S. Pat. No. 3,712,650 discloses a flange connection for connecting theends of rectangular air conditioning ducts that includes flange portionseach having a horizontal leg portion secured to the end portion of theduct and a vertical channel shaped leg for receiving the arm of anangular corner piece. A wall of the horizontal flange portion has asloping intermediate portion that permits visual access to the bendareas between the adjacent walls of the duct and ends of the duct walls.

The angular corner pieces have arm portions which each extend into anopening in the vertical channel shaped flange. The arm portions are sodimensioned vertically that the lower surface of each arm abuts thelower wall of the horizontal flange. With this arrangement the end ofthe duct wall abuts or rests against the surface of the corner piece armextending into the channel shaped opening.

Another joint assembly for connecting the ends of a pair of ducts isdisclosed in German application No. P 25 56 167 filed Dec. 13, 1975, andincludes a plurality of flange portions secured to the ends of the ductsand angular corner pieces positioned in vertically extending channelshaped openings in the respective flange portions to form a generallyrectangular frame secured to the ends of the ducts. The flange portionseach have a generally horizontal duct receiving leg and a verticalchannel shaped leg. The duct receiving leg portion has a longitudinalopening for receiving the duct end wall and one wall of the verticallyextending channel shaped leg has an inturned or inwardly rebent portionthat forms a longitudinally extending lip spaced from the lower wall ofthe horizontal duct receiving leg. The duct end portion is arranged toextend into the space between the longitudinally extending lip and thelower wall of the horizontal duct receiving leg. In position, the ductend wall abuts the inner surface of the outer vertical wall of theupstanding channel shaped leg. The arm of the corner piece is arrangedto extend into the opening above the inturned lip so that the cornerpiece arm portion is spaced from the duct end wall by the inturned lipportion. The corner pieces have arms with a curved configuration so thatpairs of facing arms in adjacent frames are intended to exert a joinderpressure on the respective frame when the corner pieces are bolted toeach other.

In the above joint assemblies, the duct end walls abut either the armsof the corner pieces or abut the inner surface of the frame channelshaped leg portion outer vertical wall. Where the end of the duct wallrests against the arm of the corner section, a space is provided betweena substantial portion of the outer vertical wall of the channel shapedleg and the end of the duct wall. Where the end of the duct wall ispositioned in the space between the inturned lip and the horizontalbottom wall, the duct end wall abuts a portion of the vertical wall ofthe frame section between the lip and the horizontal bottom wall. Ineither instance, irregularities on the surface of the duct or on thesurface of the frame portions permit leakage of air from the ductthrough the flange connection. Positioning gasket material on the outersurface of the frame portions does not eliminate this air leakage sincethe leakage is occurring within the frame portions and around the ductend wall.

In German Offenlegungschrift No. 2,221,312 published Nov. 15, 1973 afibrous gasket material is disclosed as positioned between the uppersurface of the duct end portion and the under surface of the inturnedrebent portion. French Pat. No. 1,363,255 discloses two pieces of sheetmetal joined by a fold arrangement with a sealant engaged to the edge ofone of the metal sheets. U.S. Pat. No. 3,246,918 discloses a flangeconnection in which sealing is achieved by the penetration of an end ofa duct into a mastic.

One problem encountered with the joint assemblies of the prior art isthe inability to form an air-tight seal around the duct end wallpositioned oppositely of the vertical wall of the frame section adjacentthe horizontal bottom wall of the frame section.

One proposed solution to this problem, as disclosed in the German OLSreferred to above, is positioning a longitudinally extending gasket inthe longitudinal space between the inturned rebent portion and the lowerwall of the horizontal duct receiving leg. If when the duct end wall isinserted in the duct receiving leg portion, the gasket material isrolled up against the inner surface of the vertical wall of the channelshaped leg portion, an incomplete seal is formed around the end of theduct and the inner surface of the bottom wall of the duct receiving legportion. Consequently, the end of the duct is substantially spaced fromthe inner vertical wall of the channel shaped leg portion. An air spaceis thus formed between the outside gasket on the outer surface of theframe portions and the duct edge because the outside gasket rests on thecorner pieces and does not contact the duct edge. This permits air fromthe duct to flow around the end of the duct and between the outsidesurface of the duct and the under surface of the corner piece. Thus, airleaks from the ducts at the corners of the frame connecting the ducts.

There is need for a joint assembly that provides an effective cornerseal between the duct end wall and the corner pieces that connect theadjacent flanges that form the joint frame. While it has been suggestedby the prior art joint assemblies to utilize a longitudinally extendinggasket in the flange portions to form a seal around the duct end portionin the flange portions, the gasket inside the flange portions does notprevent leakage around the corner pieces adjacent the ends of the flangeportions. In addition, even with the use of an outside gasket on thecorner pieces, unless the edge of the duct abuts the inner surface ofthe vertical wall of the flange portion, the outside gasket does notcontact the end of the duct and air will leak around the end of the ductand between the duct and the corner piece beneath the outside gasket.

SUMMARY OF THE INVENTION

In accordance with the present invention there is provided a flange typeduct joint assembly to connect the end portions of generally rectangularducts or duct sections that includes a plurality of flange portions orduct connecting flanges. A plurality of angular corner pieces areprovided for connecting adjacent flange portions to form a generallyrectangular frame. The flange portions each have an upstanding channelshaped leg portion or upstanding corner piece receiving portion and aduct receiving leg portion or duct receiving portion. The upstandingchannel shaped leg portion includes a front wall and a rear wall forminga corner piece receiving opening therebetween. The duct receiving legportion includes a top wall and a bottom wall arranged to receive an endportion of a duct therebetween. The upstanding channel shaped legportion front wall intersects the duct receiving leg bottom wall. Thecorner pieces each have a body portion or corner section and a pair oflegs extending angularly therefrom. The corner piece corner section andthe legs have a common front planar surface portion and a common rearplanar surface portion. The pair of legs are arranged to extend into thecorner piece receiving openings of the flange portion upstanding channelshaped leg portions. The corner piece body portion includes a cornerportion having a flange portion or offset corner portion extending fromthe body portion. The corner section flange portion is in juxtapositionwith the upstanding channel shaped leg portion where the front wall ofthe upstanding channel shaped leg portion intersects the bottom wall ofthe duct receiving leg portion. The corner section flange portion has afront surface and a rear surface. The flange portion front surface isdisplaced from the inner surface of the front wall of the upstandingchannel shaped leg portion. The corner piece offset corner portion ispositioned externally of the corner piece receiving openings in theadjacent duct connecting flange upstanding corner piece receivingportions. The corner piece corner section offset corner portion isdisplaced rearwardly relative to the corner piece front planar surfaceand above the duct connecting flange duct receiving portion bottom wall.The duct receiving leg portion is adapted to receive the duct endportion so that the corner edge portions of the duct end portion extendsor projects beyond the corner piece offset corner portion into abuttingrelation with an external gasket means positioned on the corner piececorner section to provide a seal for the duct corner edge portionbetween adjacent duct connecting flange portions. The external gasketmeans is positioned in overlying relation with the duct connectingflange front wall and a portion of the corner piece corner section.

A deformable gasket, such as a flowing type gasket material, ispositioned inside the flange portions and is operable to sealinglyconnect the duct end portion within the flange portions. The deformablegasket abuts the channel shaped leg portion front wall and the ductreceiving leg portion bottom wall. The deformable gasket means ispartially displaced inside the channel shaped leg portion and ductreceiving leg portion when the duct end portion is inserted into theduct receiving leg portion. With this arrangement, the gasket materialis operable to flow into sealing relation around the edge of the ductend portion in the duct receiving leg portion.

Preferably, the deformable gasket is partially displaced inside thechannel shaped leg portion and the duct receiving leg portion when theduct end portion is inserted into the duct receiving leg portion topermit the edge of the duct end portion to move into abutting relationwith the front wall of the channel shaped leg portion. The deformablegasket material has a viscosity that permits the material when displacedby movement of the duct end portion into the duct receiving leg portionto extrude out of the respective flange portions and onto the surface ofthe edge of the duct adjacent to the corner piece and onto the surfaceof the corner piece to provide an air-tight seal between the end of theduct adjacent the corner piece and the corner piece at the end of theflange portions.

Further, in accordance with the present invention an external gasket ispositioned in overlying relation with the outer surface of theupstanding channel shaped leg portion front wall and the surface of thebody of the corner section of the corner piece. The external gasket ispenetrated by the corner edge portions of the duct end portion. The ductcorner edge portions extend beyond the front surface of the corner pieceflange portion to provide a seal between the outer surface of the ductedge and the front surface of the corner piece flange portion to preventthe flow of air therebetween.

Further, in accordance with the present invention the front wall of theupstanding channel shaped member has an inner surface arranged toreceive in abutting relation the edge of the duct end portion. The outersurface of the corner piece flange portion is preferably curved ordisplaced rearwardly away from the front wall inner surface. With thisarrangement the duct end portion is permitted to extend beyond thecorner piece flange portion so that the duct edge can penetrate anexternal gasket positioned on the surface of the flange portions andcorner pieces. This arrangement provides an effective corner seal forthe duct joint assembly.

Another feature of the present invention is to provide a corner piecefor connecting end portions of duct connecting flanges. The corner pieceincludes a corner section with a rearwardly displaced flange portion.The rearwardly displaced flange portion is arranged to permit the ductcorner edge portions to project into abutting relation with an externalgasket and seal the corner edge portions of the duct.

Another feature of the present invention includes a flange type ductjoint assembly for connecting the end portions of generally rectangularducts or duct sections which assemby includes a plurality of flangeportions or duct connecting flanges. A plurality of angular cornerpieces are provided for connecting adjacent flange portions to form agenerally rectangular frame. The flange portions each have an upstandingchannel shaped leg portion or upstanding corner piece receiving portionand a duct receiving portion or duct receiving leg portion. Theupstanding channel shaped leg portion includes a front wall and a rearwall forming a corner piece receiving opening therebetween. The ductreceiving leg portion includes a top wall and a bottom wall arranged toreceive an end portion of a duct therebetween. The upstanding channelshaped leg portion front wall intersects the duct receiving leg bottomwall. The corner pieces each have a body portion or corner section and apair of legs extending angularly therefrom. The corner piece cornersection and the legs have a common front planar surface portion and acommon rear planar surface portion. The pair of legs are arranged toextend into the corner piece receiving openings of the flange portionupstanding channel shaped leg portions. The corner piece body portionhas a corner portion with a flange portion. The flange portion has anedge or edge portion. The flange portion edge is displaced from theupstanding channel shaped leg portion to permit the edge of the duct endportion to be positioned closely adjacent to the intersection of theupstanding channel shaped leg portion front wall and the duct receivingleg bottom wall. The corner piece flange portion is positionedexternally of the corner piece receiving opening in the adjacent ductconnecting flange upstanding corner piece receiving portion. The cornerpiece flange edge portion is displaced rearwardly relative to the cornerpiece front planar surface and above the duct connecting flange ductreceiving portion bottom wall so that the duct section corner edgeportion, between adjacent duct connecting flange portions, projectsbeyond the flange edge portion into abutting relation with an externalgasket means positioned on the corner piece corner section to provide aseal for the duct corner edge portion between adjacent duct connectingflange portions. The external gasket means is positioned in overlyingrelation with the duct connecting flange front wall and a portion of thecorner piece corner section. This sealing device or external gasketmeans is provided for maintaining an air-tight seal between the outersurface of the duct open end portion adjacent the corner piece and theedge of the corner piece flange portion so that the corner pieces of thegenerally rectangular frame sealingly engage the duct end portion toprevent air from within the duct flowing between the upper surface ofthe duct and the flange portion edges of the corner pieces.

Accordingly, the principal object of the present invention is to providea flange type duct joint assembly to connect the end portions ofgenerally rectangular ducts and a plurality of flange portions that areconnected to adjacent flange portions by angular corner pieces that arearranged to receive an end portion of the duct and provide an air-tightseal between the corner edge portions of the duct end portion and thesurface of the corner piece.

Another object of the present invention is to provide a seal arrangementbetween the end portion of a duct and angular corner pieces that connecta plurality of flange portions that form a frame for receiving the ductend portion to prevent flow of air from the duct between the duct endportion and the corner pieces of the frame.

A further object of this invention is to provide a corner piece thatpermits the duct corner edge portions to project into sealing relationwith an external gasket.

An additional object of this invention is to provide a flange type ductjoint assembly to connect end portions of generally rectangular ductsections that permits the duct section corner edge portions to projectinto sealing relation with an external gasket.

An additional object of this invention is to provide a flange type ductjoint assembly to connect end portions of generally rectangular ductsections that permits the duct section corner edge portions to projectinto sealing relation with an external gasket.

These and other objects of the present invention will be more completelydisclosed and described in the following specification, the accompanyingdrawings, and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a fragmentary, exploded perspective view of a flange type ductjoint assembly for connecting the end portions of a pair of ducts,illustrating a plurality of angular corner pieces for connectingadjacent flange portions to form a frame for receiving the end portionsof the ducts.

FIG. 2 is an enlarged perspective view of an angular corner piece andadjacent flange portions.

FIG. 3 is a perspective view of a corner of the end of a duct with theflange portions connected thereto and the corner piece connecting theadjacent flange portions.

FIG. 4 is a fragmentary perspective view of a corner of the end portionof a duct sealingly connected to a pair of adjacent flanges connected bya corner piece, illustrating the edge of the duct extending beyond aflange portion of the corner piece. A deformable gasket material in theflanges is shown extruded from the end of one flange but is omitted fromthe end of the other flange for purposes of illustration only to moreclearly show the relationship between the end of the flange, the flangeof the corner piece, and the end of the duct.

FIG. 5 is a perspective view of an angular corner piece, illustrating arearwardly displaced or curved flange portion extending from the innercorner of the corner piece.

FIG. 6 is a perspective view of the opposite face of the angular cornerpiece shown in FIG. 5, illustrating the configuration of the rearwardlydisplaced or curved flange portion of the corner piece.

FIG. 7 is a fragmentary perspective view of a corner piece, illustratingthe rearwardly displaced or curved flange portion.

FIG. 8 is a fragmentary sectional view of the end portion of the ductabutting the front wall of an upstanding channel shaped leg portion ofthe flange and penetrating the gasket member positioned on the flangeand the corner piece, illustrating the flange portion of the cornerpiece curved or displaced rearwardly from the front wall of the channelshaped leg portion.

FIG. 9 is a fragmentary sectional view of the end portions of a pair ofducts connected by the duct joint assembly of the present invention,illustrating the flanges secured to the ducts with the flanges abuttinga gasket therebetween.

FIG. 10 is a sectional view of a corner piece taken along the lines X--Xof FIG. 7, illustrating the configuration of a leg of the corner pieceand the curved or displaced flange portion of the corner piece.

FIG. 11 is a sectional view of a corner piece taken along lines XI--XIof FIG. 7, illustrating the configuration of a corner piece.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to the drawings and particularly to FIGS. 1-4, there isillustrated the end portion of a pair of duct sections generallydesignated by the numeral 10 in which each duct 10 has a generallyrectangular configuration with an upper duct wall 12, a lower duct wall14, and a pair of vertical duct sidewalls 16 and 18. The ducts 10 areformed in the rectangular configuration illustrated in FIG. 1 with alongitudinally extending sealed corner joint 20 between the lower ductwall 14 and the sidewall 16.

As illustrated in FIG. 3, the duct upper wall 12 and the duct sidewall18 terminates in end portions having corner portions with corner edgeportions 22 and 24. It should be understood, although not shown, thatthe other duct walls 14 and 16 terminate in similar end portions so thatthe end portions of the duct 10 extend along a plane transverse to thelongitudinal axis of the duct 10.

Each of the ducts 10 preferably is fabricated from galvanized sheetmaterial and may have various thicknesses. For example, commercial grade20 gauge duct has a thickness of between 0.906 and 1.106 millimeters.The galvanized surface of the duct walls also provides a relativelyirregular surface so that the thickness of the sheet metal forming theduct 10 is not uniform along the duct end portions.

The end portions of the pair of ducts 10 are secured to each other by apair of frame members generally designated by the numeral 26. The framemembers 26 are similar in construction and are secured to the ends ofadjacent duct sections and are connected to each other by bolts 25 andnuts 27, shown in FIG. 1 as will be described later in greater detail.Each frame 26 is formed by a plurality of duct connecting flanges thatextend outwardly from the duct wall end portion and include an upperflange portion 28, a lower flange portion 30 and a pair of side flangeportions 32 and 34. The configuration of the flange portions 28-34 areidentical and are preferably cut to a preselected length from anelongated sheet metal strip that has been roll formed into the flangeconfiguration illustrated in the drawings. Throughout the specification,the flange portions 28 and 34 and the connections therebetween will bedescribed in detail; however, it should be understood that the otherflange portions are similarly connected to the duct end portions and toeach other.

The flange portion 28 is illustrated in detail in FIGS. 2, 3, 4, 8 and9. The flange 28 has an upstanding channel shaped corner piece receivingleg portion or upstanding corner piece receiving portion generallydesignated by the numeral 36 with a front wall 38 connected to a rearwall 40 by a generally horizontal top wall 42. A shoulder 43 is formedbetween the walls 40 and 42 and is adapted to receive a longitudinalclip 41 illustrated in FIG. 9. Extending laterally at substantially aright angle from the upstanding channel shaped leg portion 36 is a ductreceiving leg portion or duct receiving portion generally designated bythe numeral 44 which has a bottom wall 46 and a top wall 48. The topwall 48 has an upturned lip portion 50 to permit the end wall of theduct to slide between the respective walls 46 and 48 so that the ductend wall is frictionally engaged between adjacent surfaces of the flangewalls 46 and 48.

In forming the profile of the flange portions, the walls 38 and 40 ofupstanding leg 36 are spaced from each other by the top wall 42 to forma longitudinally extending cavity or corner piece receiving opening 52for receiving the legs of angular corner pieces which will be describedlater. The outer vertical wall 38 has an inturned rebent portiongenerally designated by the numeral 54 that extends inwardly into theopening 52 closely adjacent the inner surface of vertical wall 40. Asillustrated in greater detail in FIG. 8, the inturned portion 54 has atear drop configuration in side elevation with an upper leg 56 and alower leg 58. The legs 56 and 58 extend angularly from the vertical wall38 and form an acute angle therewith. The lower leg 58 of inturnedportion 54 is spaced upwardly from and extends toward the inner surface60 of the lower horizontal wall 46 to form therebetween a pocketgenerally designated by the numeral 62 as seen in FIG. 3.

Suitable gasket material 64, as illustrated in FIGS. 2 and 3, ispositioned in the pocket 62 and is maintained therein by the angularrelation of lower leg 58 of inturned portion 54 and the bottomhorizontal wall 46 and the portion of the inner surface 39 of front wall38 below the inturned portion 54. The gasket material 64 has a viscositythat permits the material to flow into position by application from anozzle into the pocket 62. An example material suitable for use as thegasket material 64 is a polymeric material, such as Servaseal 5511 soldby Service Adhesives, Inc. of Maywood, Ill.

Preferably the gasket material 64 remains flowable for a substantialperiod of time at least during the assembly of the duct joint. With thisarrangement the end portion of the duct when inserted into the ductreceiving leg portion 44 partially displaces the gasket material withinthe pocket 62. The gasket material 64 sealingly connects the duct endportion to the respective flanges. Thus, an air-tight seal is formedaround the adjacent metal surfaces as will be explained hereinafter ingreater detail.

The vertical rear wall 40 of the upstanding channel shaped leg portion36 as seen in FIGS. 3 and 8 extends generally parallel to the verticalfront wall 38 to a location where the inner surface of the rear wall 40is slightly below the lower leg 58 of inturned portion 54. The rear wall40 at that location is bent to form a juncture with the top wall 48 ofthe duct receiving leg portion 44. The top wall 48 is inclined to andextends into abutting relation with the upper surface of the lower wall46 which, in turn, is bent upwardly slightly at its end portion toreceive the duct end wall and frictionally engage the duct end wallbetween adjacent surfaces of walls 46 and 48. The above describedconfiguration permits duct walls of different thicknesses to be utilizedand maintained in frictional engagement between the adjacent surfaces ofthe respective walls 46 and 48.

The vertical dimension of the pocket 62 is not critical because of thegasket material 64 positioned therein. The vertical dimension of pocket62 may be such that it is arranged to receive duct end walls ofdifferent thicknesses and the flange portions 28-34 may thus be utilizedfor joint assemblies on ducts of different wall thicknesses. It ispreferred, as illustrated in FIG. 3, that the duct walls end portions beinserted into the pockets 62 and through the gasket material 64 untilthe edges of the duct wall end portions abut the inner surfaces 39 ofthe vertical walls 38. It should be understood that a seal is obtainedwhen the edge of the duct wall end portions penetrates the gasketmaterial 64. The gasket material 64 is operable to be displaced and flowout of the pocket 62 at the end of the respective flanges to therebyform a seal around the end of the duct at the intersection of walls 38and 46 adjacent corner piece 66, as illustrated in FIG. 4.

Angular corner pieces 66, as illustrated in FIGS. 1-4 and in greaterdetail in FIGS. 5-7 and 10 and 11, have a generally planarconfiguration. Each corner piece 66 has a corner section or body portion70 and legs 72 and 74 extending angularly therefrom in substantially thesame plane as the corner section 70. The legs 72 and 74 are arranged toextend into the openings 52 of flange portions 28 and 34 while thecorner section 70 remains outside of the flange portion openings 52, asillustrated in FIGS. 1-4. The corner piece 66 has a front planar surface73 and a rear planar surface 75. The front planar surface 73 within theflange portion openings 52 is arranged to abut the inner surface 39 ofthe frame front wall 38. Also, as illustrated in FIGS. 5 and 6, forexample, corner piece corner section 70 has a common front planarsurface portion and a common rear planar surface portion with leg 72 andcorner piece corner section 70 has a common front planar surface portionand a common rear planar surface portion with leg 74. The corner piece66 has an elongated embossed portion 76, as illustrated in FIGS. 5, 6,10 and 11 which extends from a location adjacent the end portion 78 ofthe leg 72 to the corner section 70 and continues through the cornersection 70 along the other leg to a location adjacent the end portion 80of leg 74. The embossed portion 76 has a front concave surface 77 and arear convex surface 79. The convex surface 79 within the flange portionopenings abuts the front surface of the flange rear wall 40. With thisarrangement, the legs 72 and 74 have a front planar surface 73 thatabuts the rear surface 39 of flange front wall 38 and a convex surface79 that abuts the inner surface of rear wall 40.

The legs 72 and 74 have apertures 82 therein to permit dimpling of theframe portions after assembly of the frame member 26. The corner section70 has a bolt aperture 84 arranged to receive a connecting bolt. Thecorner piece 66 has shoulders 86 and 88 adjacent the upper and loweredges 90 and 92 of leg 72 and shoulders 94 and 96 adjacent the upper andlower edges 98 and 100 of leg 74, defining the boundary of the cornerpiece corner section 70 relative to legs 72 and 74. The shoulders 86,88, 94 and 96 serve as top means and are operable as stops arranged toabut ends 102 and 104 of flange portions 28 and 34, as illustrated inFIG. 3 to limit the length the legs 72 and 74 extend into the flangeportions 28 and 34. The corner piece corner section 70 has a lowercorner portion generally designated by the numeral 83 having an L-shapedflange or offset portion 85, as illustrated in FIGS. 7 and 10. Theflange portion 85 has an arcuate or offset portion 89 which is dispersedor curved rearwardly in a direction away from the corner piece frontplanar surface 73 toward the rear planar surface 75. The flange arcuateportion 89, as illustrated in FIGS. 5-7, has a front surface 91, a rearsurface 93 and an L-shaped end or edge portion 95 which is displacedrearwardly from the front planar surface 73. The edge portion 95 extendsfrom the shoulder 88 to the shoulder 96. The flange 85 is thus boundedby the shoulders 88 and 96 and the L-shaped edge portion 95.

With the above described arrangement of the corner piece 66, the legportions 72 and 74 are positioned in the openings 52 of flange portions28 and 34. The top walls 42 of the upstanding channel shaped legportions 36 serve as a stop means and abut shoulders 86 and 94 toprevent the corner section 70 of the corner piece 66 from extending intothe longitudinal openings 52. With the corner piece 66 in this positionas illustrated in FIG. 8, the front surface 91 and the L-shaped edge 95of the rearwardly displaced or curved flange or offset portion 85 aredisplaced rearwardly from the inner surface 39 of the front wall 38 andspaced above the upper surface of horizontal bottom wall 46 so as toprovide clearance for the corner edge portions 22 and 24 of the duct endportion to extend beyond the edge portion 95 and the surface 91 offlange portion 85 permitting the duct end portion to be positionedclosely adjacent to or in abutting relation with the inner surface 39 ofthe flange front wall 38. With this arrangement an air-tight seal isprovided around the corner edge portions 22 and 24 adjacent the flanges28 and 34 and by the penetration of the duct edge portions 22 and 24into a gasket 106, positioned on the corner piece corner section 70 asillustrated in FIG. 4 and as will be explained later in greater detail.

As illustrated in FIG. 11, the leg 72 of corner piece 66 has a planarsurface 73 and a concave surface 77 and upper and lower surface edges 90and 92. When the leg 72 is positioned in the opening 52 of flangeportion 28, as illustrated in FIGS. 3 and 8, the upper edge 90 of leg 72abuts the under surface of the horizontal wall 42 and the lower edge 92abuts upper leg 56 of the inturned portion 54. The rear convex surface79 of the embossment 76 abuts the inner surface of the rear wall 40while the planar front surface 73 of the leg abuts the inner surface 39of the front wall 38. With this arrangement, the leg 72 of the cornerpiece 66 abuts the surfaces of both the front wall 38 and rear wall 40in the cavity 52 and the upper edge 90 abuts the horizontal wall 42while the lower edge 92 abuts the surface of the inturned portion upperleg 56. This provides a rigid, sturdy connection between the cornerpiece leg portion and the flange portion.

As above described, the shoulders 88 and 96 are arranged to abut theends 102 and 104 of the flange portions 28 and 34 so tha the lowercorner portion 83 of the corner piece corner section 70 does not extendinto the longitudinal openings 52 of the respective flange portions.Therefore, the rearwardly curved or displaced flange portion 85 of thecorner portion 83 is in juxtaposition with the flange portion ends 102and 104. Further, as illustrated in FIGS. 4 and 8 the front surface 91of the arcuate flange portion 85 along the edge 95 is spaced rearwardlyfrom the inner surface 39 of the flange portion front wall 38. Thelongitudinal edge 95 is also spaced above the horizontal inner surface60 of the flange bottom wall 46. With this arrangement, clearance isprovided between the L-shaped edge 95 of the corner piece flange portion85 and the bottom wall upper surface 60 to permit the duct end portionsto pass between the duct receiving walls 46 and 48 into abuttingrelation with the inner surface 39 of the flange front wall 38 and thecorner edge portions 22 and 24 to pass beyond the longitudinal edge 95and flange surface 91. With this arrangement, as illustrated in FIG. 4,the end portions of the duct 10 extend into the flange portions of theframe member 26 with the exception of the L-shaped corner portions ofthe duct. The exposed portions of the duct corner edge portions 22 and24 are not embedded in the mastic seal and it is essential that a sealbe provided along these exposed corner edge portions 22 and 24 of theduct. Thus, the plane corner edges 22 and 24 of the duct end portionsextend beyond edge portion 95 of the corner piece lower corner portionflange 85 into the surface of the gasket 106.

The frame members 26 are formed by first cutting preselected lengths ofthe strips having preformed flange portion profiles. For example, frameportions 28, 30, 32 and 34 are cut from a strip of the flange shapedprofile. Four corner pieces 66 have the leg portions 72 and 74 insertedin the openings 52 in the respective upstanding channel shaped legportion 36 so that they extend into the openings 52 their entire lengthwith the shoulders 86, 88, 94 and 96 abutting the edges of therespective flange portions. With the corner pieces 66 secured in theopenings, the generally rectangular frame 26 is then secured to the endof the duct 10 by passing the duct walls 12-18 between the legs 46 and48 of the duct receiving leg portion 44. The end portions of therespective duct walls 12-18 are urged into the flange portions 28-34until the duct end wall portions, penetrate the gasket material 64 andabut the inner surfaces 39 of the frame portion vertically extendingwalls 38.

It will be apparent that due to variaions in the thickness of the ductend wall portions, the duct end portions and may be spaced slightly fromthe front wall 38 but closely adjacent thereto to the extent that theedge of the duct displaces the gasket material 64 in the pocket 62.Consequently, the flowing type gasket material extrudes outwardly aroundthe upper and lower surfaces of the duct wall end portions to seal theend portion of the duct wall in the respective pocket 62 of the flangeportion. Further, a portion of the gasket material 64 extrudeslongitudinally, as illustrated in FIG. 4, beyond the ends of the flangeportions adjacent the corner piece corner portion 83. The gasketmaterial 64 flows between a respective corner piece shoulder portion,for example shoulder 88, and the adjacent flange end portions and ontothe flange portion 85. Further when the gasket material 64 is extrudedfrom the open end of the flange it flows into the space between theupper surface of the end of the duct wall and the edge 95 of the cornerpiece flange portion 85. This arrangement provides an effective airtightseal between the flange and the duct and the corner piece and the ductwithin the flange. For purposes of illustration only the gasket material64 has been omitted from flange portion 34 shown in FIG. 4.

As illustrated in FIG. 9, pairs of ducts are positioned with the flangemembers in abutting relation with each other. A suitable relatively thingasket member 106 such as neoprene, polyethylene or the like, ispositioned between the upstanding channel shaped leg portion front walls38 on the outer surface 37 thereof and between the surfaces of thecorner pieces 66. Preferably, the gasket member 106 is formed or shapedto meet the dimensions of the duct end wall and the respective framemembers 26. Bolts 25 are inserted through the respective apertures 84,and nuts 27 are threadedly secured to the bolts 25 to thus secure thecorner pieces 66 to each other and, in turn, secure the respective framemembers 26 to each other with the ducts 10 secured thereto.

With this arrangement, the frame members 26 provide a joint assembly forsecuring the duct members 10 to each other and to form an air-tight sealtherebetween. The configuration of the flange portions permits ductmembers having walls of different thicknesses to be utilized with theframe portions having the same dimension. The edges of the duct wallsextend into the flowing type gasket material 64 in the longitudinalopenings 52 to provide an air-tight seal between the undersurface of theduct wall and the uppersurface of the duct receiving leg portion andfurther around the duct end wall between the uppersurface of the ductwall and the innersurface 39 of front wall 38. In addition the flowingtype gasket material 64 is effective to form an air-tight seal where thesurfaces of duct walls or the walls of the frame portions are irregulardue to the coating applied to the surface during the galvanizingoperation.

Further it will be apparent from the present invention that byrearwardly curving or displacing the corner piece flange portions 85that form the corner piece corner portion 83, the duct corner edgeportions 22 and 24 are operable to extend into or penetrate the gasketmember 106 which is positioned between the upstanding channel shaped legportions 36 in overlying relation with the corner piece lower cornerportions 83. In this manner air from within the duct is prevented fromflowing around the duct end wall and between the upper surface of theduct and the surface of the corner piece flange edge 95.

According to the provisions of the patent statutes I have explained theprinciple preferred construction and mode of operation of my inventionand have illustrated and described what I now consider to represent itsbest embodiments. However, it should be understood that, within thescope of the appended claims, the invention may be practiced otherwisethan as specifically illustrated and described.

I claim:
 1. A flange type duct joint assembly to connect end portions ofgenerally rectangular duct sections comprising,duct sections having agenerally rectangular configuration with end portions, said duct sectionend portions having corner portions with corner edge portions, aplurality of duct connecting flanges, said duct connecting flanges eachhaving an upstanding corner piece receiving portion with a front wall, arear wall and a corner piece receiving opening therebetween, said ductconnecting flanges each having a duct receiving portion with a top walland a bottom wall, said duct connecting flange upstanding corner piecereceiving portion front wall intersecting said duct receiving portionbottom wall, a plurality of corner pieces for connecting adjacent ductconnecting flanges, said corner pieces each having a corner section anda pair of legs extending angularly from said corner section, said cornerpiece corner section and said legs having a common front planar surfaceportion and a common rear planar surface portion, said corner piece legsarranged to extend into said duct connecting flange upstanding cornerpiece receiving opening to connect adjacent duct connecting flanges andform a generally rectangular frame, said duct section end portionsarranged to extend into said duct connecting flange duct receivingportions between said top wall and said bottom wall and intosubstantially abutting relation with said duct connecting flangeupstanding corner piece receiving portion front wall, external gasketmeans positioned in overlying relation with said duct connecting flangefront wall and a portion of said corner piece corner section, saidcorner piece corner section having an offset corner portion displacedrearwardly from said front planar surface, said corner piece offsetcorner portion positioned externally of said corner piece receivingopenings in said adjacent duct connecting flange upstanding corner piecereceiving portions, and said corner piece corner section offset cornerportion displaced rearwardly relative to said corner piece front planarsurface and above said duct connecting flange duct receiving portionbottom wall so that said duct section corner edge portion, betweenadjacent duct connecting flange portions, projects beyond said cornerpiece offset portion into abutting relation with said external gasketmeans positioned on said corner piece corner section to provide a sealfor said duct corner edge portion between adjacent duct connectingflange portions.
 2. A flange type duct joint assembly as set forth inclaim 1 in which,said duct connecting flanges each having end portionsand an inturned front wall portion, said corner piece corner sectionoffset corner portion having a generally L-shaped configuration with anedge portion positioned adjacent each of said legs, said offset cornerportion edge portions abutting said duct connecting flange inturnedfront wall portion to limit the length of said corner piece extendinginto said end portions of said respective adjacent duct connectingflange upstanding corner piece receiving portions.
 3. A flange type ductjoint assembly as set forth in claim 1 in which,said corner piece has anembossment extending along said pair of legs with a front concavesurface along said front planar surface portion and a rear convexsurface along said rear planar surface portion, said leg front planarsurface portion abutting said upstanding corner piece receiving portionfront wall and said convex surface abutting said upstanding cornerreceiving portion rear wall.
 4. A flange type duct joint assembly toconnect end portions of generally rectangular duct sectionscomprising,duct sections having a generally rectangular configurationwith end portions, said duct section end portions having corner portionswith corner edge portions, a plurality of duct connecting flanges, saidduct connecting flanges each having an upstanding corner piece receivingportion with a front wall, a rear wall and a corner piece receivingopening therebetween, said duct connecting flanges each having a ductreceiving portion with a top wall and a bottom wall, said ductconnecting flange upstanding corner piece receiving portion front wallintersecting said duct receiving portion bottom wall, a plurality ofcorner pieces for connecting adjacent duct connecting flanges, saidcorner pieces each having a corner section and a pair of legs extendingangularly from said corner section, said corner piece corner section andsaid legs having a common front planar surface portion and a common rearplanar surface portion, said corner piece legs arranged to extend intosaid duct connecting flange upstanding corner piece receiving opening toconnect adjacent duct connecting flanges and form a generallyrectangular frame, said duct section end portions arranged to extendinto said duct connecting flange duct receiving portions between saidtop wall and said bottom wall and into substantially abutting relationwith said duct connecting flange upstanding corner piece receivingportion front wall, external gasket means positioned in overlyingrelation with said duct connecting flange front wall and a portion ofsaid corner piece corner section, said corner piece corner sectionhaving a corner portion, a flange portion extending from said cornersection corner portion, said flange having an edge portion displacedrearwardly from said corner piece front planar surface portion, saidcorner piece flange portion positioned externally of said corner piecereceiving opening in said adjacent duct connecting flange upstandingcorner piece receiving portion, and said corner piece flange edgeportion displaced rearwardly relative to said corner piece front planarsurface and above said duct connecting flange duct receiving portionbottom wall so that said duct section corner edge portion, betweenadjacent duct connecting flange portions, projects beyond said flangeedge portion into abutting relation with said external gasket meanspositioned on said corner piece corner section to provide a seal forsaid duct corner edge portion between adjacent duct connecting flangeportions.
 5. A flange type duct joint assembly as set forth in claim 4in which,said corner piece corner section flange portion having agenerally L-shaped configuration.
 6. A duct joint assembly forconnecting the end portions of generally rectangular ducts comprising,apair of duct sections having a generally rectangular configuration withend portions, said duct section end portions having corner portions withcorner edge portions, a plurality of duct connecting flanges, said ductconnecting flanges each having an upstanding corner piece receivingportion with a front wall, a rear wall and a corner piece receivingopening therebetween, said duct connecting flanges each having a ductreceiving portion with a top wall and a bottom wall, said ductconnecting flange upstanding corner piece receiving portion front wallintersecting said duct receiving portion bottom wall, a plurality ofcorner pieces for connecting adjacent duct connecting flanges, saidcorner pieces each having a corner section and a pair of legs extendingangularly from said corner section, said corner piece corner section andsaid legs having a common front planar surface portion and a common rearplanar surface portion, said corner piece legs arranged to extend intosaid duct connecting flange upstanding corner piece receiving opening toconnect adjacent duct connecting flanges and form a generallyrectangular frame, said duct section end portions arranged to extendinto said duct connecting flange duct receiving portions between saidtop wall and said bottom wall and into substantially abutting relationwith said duct connecting flange upstanding corner piece receivingportion front wall, said corner piece corner section having an offsetcorner portion displaced rearwardly from said front planar surface, saidcorner piece offset portion positioned externally of said corner piecereceiving openings in said adjacent duct connecting flange upstandingcorner piece receiving portions, pairs of said duct sections with saidgenerally rectangular frames on said duct end portions positioned withsaid duct connecting flange corner piece receiving portion front wallsin adjacent relation to each other, a gasket member positioned betweensaid duct connecting flange portion corner piece receiving front wallsand said corner piece corner sections, said corner piece corner sectionoffset corner portions displaced rearwardly relative to said cornerpiece front planar surface and above said duct connecting flange ductreceiving portion bottom wall so that said adjacent duct section corneredge portions, between adjacent duct connecting flange portions, projectbeyond said corner piece offset portions to a location adjacent saidfront wall of said duct connecting flange upstanding corner piecereceiving portions, and means for securing said rectangular frames toeach other to connect said duct sections and urge said duct sectioncorner edge portions into said gasket member between adjacent ductconnecting flange end portions to provide an air-tight seal at thecorner portions of said connected duct sections and urge said upstandingcorner piece receiving portion front walls against said gasket member toform an air-tight seal between said rectangualr frames.
 7. A duct jointassembly for connecting the end portions of generally rectangular ductscomprising,a pair of duct sections having a generally rectangularconfiguration with end portions, said duct section end portions havingcorner portions with corner edge portions, a plurality of ductconnecting flanges, said duct connecting flanges each having anupstanding corner piece receiving portion with a front wall, a rear walland a corner piece receiving opening therebetween, said duct connectingflanges each having a duct receiving portion with a top wall and abottom wall, said duct connecting flange upstanding corner piecereceiving portion front wall intersecting said duct receiving portionbottom wall, a plurality of corner pieces for connecting adjacent ductconnecting flanges, said corner pieces each having a corner section anda pair of legs extending angularly from said corner section, said cornerpiece corner section and said legs having a common front planar surfaceportion and a common rear planar surface portion, said corner piece legsarranged to extend into said duct connecting flange upstanding cornerpiece receiving opening to connect adjacent duct connecting flanges andform a generally rectangular frame, said duct section end portionsarranged to extend into said duct connecting flange duct receivingportions between said top wall and said bottom wall and intosubstantially abutting relation with said duct connecting flangeupstanding corner piece receiving portion front wall, said corner piececorner section having a corner portion, a flange portion extending fromsaid corner section corner portion, said flange portion having an endportion displaced rearwardly from said corner piece front planarsurface, said corner piece flange portion positioned externally of saidcorner piece receiving openings in said adjacent duct connecting flangeupstanding corner piece receiving portions, pairs of said duct sectionswith said generally rectangular frames on said duct end portions withsaid duct connecting flange corner piece receiving portion front wallsin adjacent relation to each other, a gasket member positioned betweensaid duct connecting flange corner piece receiving portion front wallsand said corner piece corner sections, said corner piece flange endportions displaced rearwardly relative to said corner piece front planarsurface and above said duct connecting flange duct receiving portionbottom wall so that said adjacent duct section corner edge portions,between adjacent duct connecting flange portions, projects beyond saidcorner piece flange end portion to a location adjacent said front wallof said duct connecting flange, and means for securing said rectangularframes to each other to connect said duct sections and urge said ductsection corner edge portions into said gasket member, between adjacentduct connecting flange portions, to provide an air-tight seal at thecorner portions of said connected duct sections and urge said upstandingcorner piece receiving portion front walls against said gasket member toform an air-tight seal between said rectangular frames.